1. Field of the Invention
The invention relates generally to concrete finishing trowels and, more particularly, to a transport system for a powered finishing trowel. The invention additionally relates to a concrete finishing trowel, such as a riding trowel, having an integrated transport system that enables wheeled transport of the trowel within a worksite and to and from a worksite.
2. Description of the Related Art
A variety of machines are available for smoothing or otherwise finishing wet concrete. These machines range from simple hand trowels, to walk-behind trowels, to self-propelled riding trowels. Regardless of the mode of operation of such trowels, the powered trowels generally include one to three rotor assemblies that rotate relative to the concrete surface.
Riding concrete finishing trowels can finish large sections of concrete more rapidly and efficiently than manually pushed or guided hand-held or walk behind finishing trowels. Riding concrete finishing trowels typically include a frame having a cage that typically encloses two, and sometimes three or more, rotor assemblies. Each rotor assembly includes a driven shaft and a plurality of trowel blades mounted on and extending radially outwardly from the bottom end of the driven shaft. The driven shafts of the rotor assemblies are driven by one or more engines mounted on the frame and typically linked to the driven shafts by gearboxes of the respective rotor assemblies.
The weight of the finishing trowel, including the operator, is transmitted frictionally to the concrete surface by the rotating blades, thereby smoothing the concrete surface. The pitch of individual blades can be altered relative to the driven shafts via operation of a lever and/or linkage system during use of the machine. Such a construction allows the operator to adjust blade pitch during operation of the power trowel. As is commonly understood, blade pitch adjustment alters the pressure applied to the surface being finished by the machine. This blade pitch adjustment permits the finishing characteristics of the machine to be adjusted. For instance, in an ideal finishing operation, the operator first performs an initial “floating” operation in which the blades are operated at low speeds (on the order of about 30 rpm) but at high torque. Then, the concrete is allowed to cure for another 15 minutes to one-half hour, and the machine is operated at progressively increasing speeds and progressively increasing blade pitches up to the performance of a finishing or “burning” operation at the highest possible speed—preferably above about 150 rpm and up to about 200 rpm.
During use, the riding trowel is supported by the engagement between the blades and the underlying concrete material. The blades may rest directly on the concrete or on pans. To some extent, the weight of the machine assists the finishing process.
Although the weight of the machine can be beneficial for providing efficient, robust, and powerful trowel operation, the weight of the machine is also detrimental to non-use transportation of the trowel, i.e. while moving the trowel within the worksite or to or from a worksite without operating the blades. Commonly, supplemental equipment, such as a skid loader, a backhoe, or the like, is utilized to move the machine to and from a work surface. Some concrete finishing trowels are fitted with lift points for attachment to a chain for this purpose. These machines experience difficulty in moving the trowel in certain work environments. For instance, for large slab on grade jobs where a number of pours are required to complete a floor, the green concrete is unable to support the heavy machinery for several weeks after a pour. Forklifts and similar devices therefore cannot access the trowels for transport.
Further, forklifts and other prior art transport systems used in lieu of on-board wheel transports are typically constructed to support weights of approximately between 1600-2300 pounds; however, concrete finishing trowels may weigh in excess of 2300 pounds. For instance, some known trowels may weigh as much as 2800 pounds, making the prior art transport systems unsuitable for use therewith. Alternatively, when no such equipment is available or the trowel must be used in a location which is not accessible by or otherwise cannot accommodate such equipment, two or more laborers are required to manually lift and move the machine. This is a labor intensive and physically demanding technique for moving such machines.
Previous trowel transport systems have been disclosed which include a number of wheels or casters that are securable to the frame of the trowel. These transport systems typically take the form of “wheel kits” that are sold as aftermarket accessories. The wheel kits comprise a number of wheel assemblies that are irremovably attached to the trowel. One such removable wheel kit or “dolly” is disclosed in U.S. Pat. No. 5,238,323 to Allen et al. The wheel kit disclosed in the Allen '323 patent includes a pair of wheel assemblies secured to generally opposite sides of the exterior of the cage of a riding trowel. A separate jack is provided for each wheel assembly so that each jack independently raises and lowers a separate wheel assembly relative to the frame. When lowered, the wheels support the trowel such that a single user can move the entire trowel by simply pushing or pulling it in an intended direction.
Although such systems enhance the mobility of power trowels, they are not without their drawbacks.
For instance, because the wheel assemblies of the Allen '323 patent are located outboard of the cage, they increase the overall footprint of the machine. Increasing the footprint of the machine increases the space occupied by the machine. Accordingly, it may prevent the machine from being transported in the beds of some trucks without removing the wheel assemblies. Increasing the footprint of the machine also detracts from a user's ability to position the machine close to the perimeter of an area to be worked (commonly referred to as a “pour area”) or an obstacle in or adjacent to a pour area. This limitation is problematic because users of finishing machines prefer that the machine finish as much of the pour area as possible. The areas that cannot be finished due to the interference between the wheel assemblies and the obstructions must be finished by hand, increasing the amount of hand work associated with a given pour. This problem can be avoided only by removing the wheel assemblies prior to commencing a finishing operation.
Transport systems such as the one disclosed in U.S. Pat. No. 5,238,323 are also relatively inefficient. To raise the machine, the operator must manually operate two separate jacks on opposite sides of the machine. In addition, unless care is taken to operate both jacks the same amount, one side of the machine may be higher than the other during transport, reducing the stability and maneuverability of the machine. Moreover, the wheel kit of the '323 patent is not integrated into the trowel but, rather, is coupled to the machine as an accessory that typically is installed and removed at the worksite. Like any accessory, these wheel kits are susceptible to being lost, left behind, or damaged at job sites because they are set aside when not in use.
U.S. Pat. No. 7,771,139 to Grahl discloses a transport system in which two or more spaced wheels are concurrently movable by manual manipulation of a single lifting jack to adjust the position of the wheels relative to the blades of the finishing machine. The wheel assemblies of the '139 patent also are located inside the “footprint” of the machine, permitting the machine to be operated with the wheel assemblies installed without interference from obstructions in or adjacent the pour area. They also are integrated into the remainder of the machine. While the device of the '139 patent is thus an improvement over the '323 patent, the presence of even a single jack may prove to be cumbersome during maintenance of the trowel. Manually operating a jack also is labor intensive. The need to manually actuate the jack or other lifting mechanisms of traditional wheel kits is especially problematic with large, hydraulically powered trowels. These trowels typically have an internal combustion engine coupled to the rotor assemblies by a hydrostatic drive system including a pump and multiple hydraulic motors, one of which is provided for each rotor assembly. The trowels are steered by tilting the rotor assemblies using hydraulic cylinders. Each rotor assembly may have a diameter of 5 feet, rendering the trowel over 10 feet long. The combined weight of the trowel and the operator may exceed 2,500 lbs—triple that of traditional manually steered powered trowels having a mechanical gearbox coupling each rotor assembly to the internal combustion engine. This dramatic difference in weight renders traditional manually actuated jacks and their associated wheel kit components ill-suited for use with hydraulically powered trowels.
Accordingly, there is also a need for a wheeled transport system for a concrete finishing trowel that requires less effort to deploy than previously-known transport systems.
There is also a need for a trowel transport system which is integrated into the trowel and which, therefore, need not be attached to the trowel by the operators and is not at risk of damaged when removed from the trowel or of being lost.
There is also a need for an easily-deployed concrete finishing trowel transport system that does not increase the footprint of the machine. A transport system that is integrated into a powered trowel and that eliminates the need for an external lifting mechanism such as a jack is also desired.
It is further desired to provide a trowel transport system that can be implemented into a number of machine configurations as well as one that is relatively simple to operate, inexpensive to produce, and simple to maintain.